1. Field of the Related Art
This invention relates to a bridge mechanism for an acoustic guitar.
2. Description of the Related Art
A prior art acoustic guitar 60, such as a folk guitar, is shown in FIG. 7. A hollow resonant box 70 amplifies the vibrating sound of the strings under the table or soundboard 62 of the guitar body 61. The resonant box 70 is completed by back 63 and side plate 64.
Guitar strings 65 are installed at a pedestal or tailpiece 68 that is fixed to the surface of the soundboard 62. The end of each string is held by means of a wedge-like fixing pin 69. The string is rolled onto a tuning bolt or peg 67 at the other end of neck 66.
In contrast to the acoustic guitar, in an electric guitar the vibrations of the strings are picked-up and amplified electronically, using a magnetic force generated by the vibrating strings. Accordingly, the body of an electric guitar ordinarily is solid and is equipped with a bridge mechanism comprising a base plate made of a metal and a plurality of bridge members (saddle members) made of metal as are described in the Official Publication of Utility Model Registration No. 2560349, to cite an example.
As in the case of the above-described acoustic guitar, the guitar strings of the electric guitar are held at the bridge member of the bridge mechanism at one end and rolled onto the tuning bolt of the neck at the other end. In electric guitar bridge members individual adjustment of the string height and length are possible, as compared with the base plate. The string height and length normally are capable of very fine adjustment.
In the acoustic guitar, on the other hand, it is not possible to make a fine adjustment of the string height and the string length. Accordingly, performers accustomed to an electric guitar, which has become the main form of guitar in use in recent years, tend to complain about this lack of fine string adjustment in acoustic guitars. In addition, if it becomes possible to make a fine adjustment of the string height and the string length of an acoustic guitar, the breadth of its performance capabilities will be expanded.
Nevertheless, loading an acoustic guitar with a bridge mechanism that is capable of affording a fine adjustment of the height and the length of each guitar string entails the following problems:
The surface of the soundboard of the acoustic guitar has normal curvature with a radius approximately in the range between 4000 and 6000 millimeters. Variations in the curved surface stem from such natural conditions as the manufacturing requirements and the humidity, etc. But this makes it extremely difficult to adhere a base plate made of metal tightly to the surface of the soundboard.
Further, if the base plate does not adhere tightly to the surface of the soundboard, the vibrations of the guitar strings are not transmitted accurately to the guitar body, and there are other undesirable sounds, etc. that are produced, thereby reducing the quality of the sound, for example.
Even when a base plate made of metal has been tightly fixed to the surface of the soundboard, the soundboard tends to be deformed in the horizontal direction as compared with the guitar strings because of changes in the temperature or humidity, so that the tight adherence between the soundboard and base plate tending to deteriorate and deform the instrument.